The effect of a prolonged 2,4-dichlorophenoxyacetic-acid treatment on transpiration and stomatal distribution in tomato leaves.

The effect of 2,4-dichlorophenoxyacetic acid applied during plant development on transpiration rate and distribution of stomata was studied in the wilty tomato mutant, flacca, and the normal cultivar, Rheinlands Ruhm. The rate of transpiration per unit leaf area was higher in treated than untreated leaves. Stomatal density in treated leaves did not increase; the stomates were able to open and close, and their aperture width under light was not greater than in untreated leaves. The ratio between stomata on the upper and lower leaf surfaces was higher in treated plants.